In recent years, touch screens have taken a significant share of the mobile display market. The touch screen is operated by touching the screen directly with the human hand or with an object that is used for input, without using input devices such as a keyboard or a mouse. Accordingly, most operations on the screen, including internet access, moving images, and multiple touches, are easily performed, and thus the touch screen is one of the most convenient user interfaces.
Examples of methods for realizing the touch screen include a resistive overlay method, a capacitive overlay method, an ultrasonic method, an optical method, an infrared method, etc. The touch screen based on the resistive overlay method has problems in that it has low durability and light transmittance and in that multi-touch cannot be realized in practice.
One method for solving the problems associated with the resistive overlay method is the capacitive overlay method. The capacitive overlay method is a method in which the touch screen is operated by sensing micro-current generated by the human body. The touch screen based on the capacitive overlay method uses a constant current, and thus has excellent touch sensitivity, and particularly, enables the implementation of a multi-touch function. In addition, it has advantages in that, because it uses glass as a cover, it has good durability and a light transmittance of 90% or higher and gives an elegant feeling. However, it has shortcomings in that the input method is limited and the production cost is high.
In a conventional method for manufacturing an integrated touch screen panel, bezel layers are formed using ink by a screen printing method, and thus the thicknesses thereof are mostly 6 μm or more, and 10 μm on average.
However, when a sensor layer is applied to a bezel layer having this thickness, a short circuit occurs due to the difference in height between the bezel layer and the substrate, making it difficult to drive the sensor.
For this reason, there has been a need for a material that can substitute for conventional ink for forming bezels and is thin, is gradually tapered, and has sufficient light-shielding properties. Particularly, because the resistance of a touch sensor is reduced in a high-temperature process for forming it, there has been the requirement to solve the problem of deterioration of the properties of a touch screen panel, which is required to exhibit high resistance, attributable to the bezel material.
In addition, there has been a need to develop a bezel material having excellent chemical resistance in order to prevent a peeling phenomenon from occurring in an etching process and a stripping process, which are used to form metal wiring on a bezel layer.